TokuDB MRR completely broken in 5.6

mysqld: /ssd/percona/8.0/percona-server/sql/handler.cc:6988: int DsMrr_impl::dsmrr_init(handler*, RANGE_SEQ_IF*, void*, uint, uint, HANDLER_BUFFER*): Assertion `h->inited == handler::RND' failed.
17:05:24 UTC - mysqld got signal 6 ;
This could be because you hit a bug. It is also possible that this binary
or one of the libraries it was linked against is corrupt, improperly built,
or misconfigured. This error can also be caused by malfunctioning hardware.
Attempting to collect some information that could help diagnose the problem.
As this is a crash and something is definitely wrong, the information 
collection process might fail.
Please help us make Percona Server better by reporting any
bugs at http://bugs.percona.com/

key_buffer_size=1048576
read_buffer_size=131072
max_used_connections=1
max_threads=152
thread_count=1
connection_count=1
It is possible that mysqld could use up to
key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 61233 K bytes of memory
Hope that's ok; if not, decrease some variables in the equation.

Thread pointer: 0x7fc0b808a6a0
Attempting backtrace. You can use the following information to find out
where mysqld died. If you see no messages after this, something went 
terribly wrong...
stack_bottom = 7fc121762dd0 thread_stack 0x40000
/ssd/percona/8.0/percona-server-install-5.7/bin/mysqld(my_print_stacktrace+0x38)[0x18c0037]
/ssd/percona/8.0/percona-server-install-5.7/bin/mysqld(handle_fatal_signal+0x411)[0xeb15b8]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x10330)[0x7fc12913a330]
/lib/x86_64-linux-gnu/libc.so.6(gsignal+0x37)[0x7fc128577c37]
/lib/x86_64-linux-gnu/libc.so.6(abort+0x148)[0x7fc12857b028]
/lib/x86_64-linux-gnu/libc.so.6(+0x2fbf6)[0x7fc128570bf6]
/lib/x86_64-linux-gnu/libc.so.6(+0x2fca2)[0x7fc128570ca2]
/ssd/percona/8.0/percona-server-install-5.7/bin/mysqld(_ZN10DsMrr_impl10dsmrr_initEP7handlerP15st_range_seq_ifPvjjP17st_handler_buffer+0x4f3)[0xf4ca61]
/ssd/percona/8.0/percona-server-install-5.7/lib/mysql/plugin/ha_tokudb.so(_ZN9ha_tokudb21multi_range_read_initEP15st_range_seq_ifPvjjP17st_handler_buffer+0x4e)[0x7fc11843bbae]
/ssd/percona/8.0/percona-server-install-5.7/bin/mysqld(_ZN18QUICK_RANGE_SELECT5resetEv+0x47b)[0x175a2ad]
/ssd/percona/8.0/percona-server-install-5.7/bin/mysqld(_Z21join_init_read_recordP7QEP_TAB+0xab)[0x1521831]
/ssd/percona/8.0/percona-server-install-5.7/bin/mysqld(_Z10sub_selectP4JOINP7QEP_TABb+0x231)[0x151ea43]
/ssd/percona/8.0/percona-server-install-5.7/bin/mysqld[0x151e3c7]
/ssd/percona/8.0/percona-server-install-5.7/bin/mysqld(_ZN4JOIN4execEv+0x66b)[0x151c32b]
/ssd/percona/8.0/percona-server-install-5.7/bin/mysqld(_Z12handle_queryP3THDP3LEXP12Query_resultyy+0x38f)[0x15bee5f]
/ssd/percona/8.0/percona-server-install-5.7/bin/mysqld[0x156f116]
/ssd/percona/8.0/percona-server-install-5.7/bin/mysqld(_Z21mysql_execute_commandP3THDb+0xf07)[0x1567bea]
/ssd/percona/8.0/percona-server-install-5.7/bin/mysqld(_Z11mysql_parseP3THDP12Parser_state+0x735)[0x1570209]
/ssd/percona/8.0/percona-server-install-5.7/bin/mysqld(_Z16dispatch_commandP3THDPK8COM_DATA19enum_server_command+0xca7)[0x1564539]
/ssd/percona/8.0/percona-server-install-5.7/bin/mysqld(_Z10do_commandP3THD+0x521)[0x1563373]
/ssd/percona/8.0/percona-server-install-5.7/bin/mysqld(handle_connection+0x2a4)[0x16aee42]
/ssd/percona/8.0/percona-server-install-5.7/bin/mysqld(pfs_spawn_thread+0x170)[0x1d4ec33]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x8184)[0x7fc129132184]
/lib/x86_64-linux-gnu/libc.so.6(clone+0x6d)[0x7fc12863effd]

Trying to get some variables.
Some pointers may be invalid and cause the dump to abort.
Query (7fc0b8271900): select a,filler from t3 where a >= 'c-1011=w' and a <= 'c-1015=w'